This invention relates to a retrace pulse generator for a deflection system.
Almost all deflection systems such as utilized in television receivers utilize a deflection current generating circuit to supply a substantially linearly changing current to a deflection winding during a trace interval. A retrace pulse, which conventionally is derived from any one of a number of types of free-running oscillators, resets the deflection generating circuit periodically to provide for periodic trace and retrace intervals. Synchronizing pulses which are recovered from the composite video signal provide for synchronization of the phase and frequency of the free-running oscillator.
Free-running oscillators of the type aforementioned generally utilize circuits wherein the probability of erroneous synchronization in response to noise pulses present in the composite video signal between synchronizing pulses is increasing and is exponentially related to the elapsed time after a first synchronizing pulse. Some improvements to the free-running oscillators of the type aforementioned have provided for distortion of the exponential relationship to enhance noise immunity. However, a system which provides for absolute noise immunity over a large portion of the interval of time between synchronizing pulses would improve system performance.